Pancreas | Organs | MUSC Digestive Disease Center Map/Directions Pancreas The pancreas and bile duct (biliary) systems together form an important part of the digestive system. The pancreas and liver produce juices (pancreatic juice and bile) which help in the process of digestion (i.e. the breakdown of foods into parts which can be absorbed easily and used by the body). The pancreas is about the same size and shape as a small banana, and lies in the upper abdomen, towards the back, near the spine. The pancreas is solid (acinar tissues), and contains drainage tubes (the pancreatic ductal system). The pancreatic juices are made in the acinar tissues, and passed by secretion into the tubes (ducts) for transport into the duodenum . The exit hole into the duodenum is called the papilla of Vater. The biliary juices (bile) are made in the tissues of the liver (hepatic parenchyma), and then pass into the biliary ductal system (picture).

Like a river, these ducts gradually join together to form one stream in the main bile duct, which exits (along with the pancreatic duct) into the duodenum at the "papilla of Vater." The gallbladder is a storage chamber for bile, joined to the side of the bile duct by another small tube  the cystic duct. The anatomy (design) of the biliary and pancreatic ducts is not the same in every person. Variations can be important; some can cause medical problems, others may make treatment more difficult or complicated. Papilla of Vater and Minor (Accessory) Papilla The main papilla of Vater is a small nipple-like structure on the wall of the duodenum, in its "second part." The duodenum is the upper part of the small intestine , into which food flows from the stomach . The papilla forms the main exit hole for the bile and pancreatic juices which flow down the bile duct and pancreatic duct. Rarely there are two separate holes close together within the same papillary nipple. The papilla remains closed at rest, because of the activity of a muscular valve (sphincter).

The sphincter (of Oddi) surrounds the exit of the bile duct and pancreatic duct. It opens by reflex action when foods enter the stomach, so that juices can be released to help in their digestion. In most people there is a second smaller (minor, or accessory) papilla, situated about 2 cm (3/4 inch) above the main papilla, and slightly to its right. This is the exit hole for Santorini's duct. The minor papilla occasionally acts as a useful safety valve when the main papilla is not able to function correctly, but becomes the main site of drainage for pancreatic juices in the congenital variant called pancreas divisum. Bile Duct System and Gallbladder The bile duct (biliary) system provides the channels through which bile is transported from the liver to the duodenum (through the papilla of Vater). The liver is found in the right upper corner of the abdomen, immediately below the diaphragm. In health it weighs 3-4 pounds. It is divided into right and left lobes, and each of these have several segments. The bile ducts start as tiny tubes called sinusoids which lie between rows of liver cells called hepatocytes.

These liver cells make bile, and pass it into the tiny canals (cannaliculi). The small ducts join together like branches to form the main biliary tree, with one trunk which is formed just outside the surface of the liver. This is called the common hepatic duct. The gallbladder is a collection sac for bile, which enters and leaves through a narrow tube called the cystic duct. The gallbladder is about the size of an egg when full. The bile duct below the cystic duct is usually called the common bile duct. The common bile duct and the common hepatic duct together constitute the main bile duct. The lower end of the bile duct sweeps around behind the duodenum and through the head of the pancreas before joining the pancreatic duct at the main papilla (of Vater). Pancreatic Duct System There is a main pancreatic duct which collects juices from all the branches of the pancreatic stream, and exits at the main papilla of Vater. The pattern of these branches varies considerably, but this does not matter.

However, there is often another important duct (named after Santorini) that connects the main pancreatic duct to another small papilla (the minor or accessory papilla) which is found about 2 cm (3/4 inch) above the main papilla of Vater in the duodenum. This (normal) arrangement comes about as a result of complex reorganization during fetal development. Early in the development of the embryo, the pancreas is in two parts (dorsal and ventral elements). These parts usually join together to form one pancreas between six and eight weeks of pregnancy. Even after joining, the santorini stays open or "patent," and drains into the minor papilla in over half of patients. Thus, the patient who develops a problem at the main papilla (like a stone or tumor) may not develop any symptoms of pancreatic obstruction if Santorini's duct and the minor papilla are open, and can take over the drainage function. An X-ray image of the biliary tree during an ERCP procedure. However, this fusion (joining) does not happen in about one in twelve people (at least in western populations). Then the pancreas remains divided (so called "pancreas divisum").

In patients with divisum, the largest (dorsal) part of the pancreas drains through Santorini's duct and the minor papilla, while only a small part (the ventral pancreas) drains through the usual (major) papilla. The importance of this is that the minor papilla may be too small to allow easy passage of the pancreatic juices; and some patients with pancreas divisum can develop attacks of pain and pancreatitis as a result due to this relative narrowing. There are other rarer variations of pancreatic anatomy. Annular pancreas describes a congenital condition in which one of the branches of the pancreas swings all around the duodenum; this can narrow the duodenum sufficiently to cause obstruction and require operation. This condition usually presents in infancy (for obvious reasons), but can be discovered only later in life if the narrowing is not so tight, and sometimes when attacks of pancreatitis are associated with it. Other anomalies of pancreas development produce interesting pictures, but are not of clinical importance. Function & Control The tissues of the pancreas (acinar cells) produce a clear digestive fluid made up of bicarbonate, and enzymes.

Bicarbonate is alkaline, and helps digestion by neutralizing the stomach acid containing the food as it passes into the duodenum. The enzymes are more important. These are designed to help breakdown (digest) complex carbohydrates (sugars), proteins, and fats in the food. The main enzymes are called amylase, proteases (trypsin, chymotrypsin), and lipase. The enzyme and bicarbonate secretions together are called the "exocrine" function of the pancreas. The bile ducts function as a drainage system for the liver. Bile is a bitter dark fluid, composed of bile acids, bile pigments, bilirubin, cholesterol and other fats, water and electrolytes. Some of these constituents are useful for digestion, others are simply waste products (i.e. cholesterol). The gallbladder acts to store bile, and make it more concentrated by removing water. Although thin, the gallbladder wall has muscle tissue, so that it can contract and empty when necessary.

Production of the bile and pancreas juices and their release into the duodenum through the papilla of Vater are controlled by abdominal nerves and also specific messengers (hormones) which pass to their targets through the bloodstream. These systems also control contractions of the gallbladder, and relaxation of the sphincter of Oddi (the muscular valve within the papilla of Vater). Together these insure that the juices are produced and released into the duodenum only when they are needed, that is when food arrives from the stomach ready for final digestion, and subsequent absorption. The pancreas also has an "endocrine" function  the production of insulin and other important hormones. These are produced in separate tissues within the pancreas (islets of Langerhans), and passed directly into the blood stream (rather than into the pancreatic duct). Insulin is very important for control of sugar levels in the blood; lack of insulin results in diabetes. The pancreas produces many other enzymes (such as somatostatin, pancreatic polypeptide, glucagon, etc.), the functions of which are of less immediate importance.

Glucagon helps counteract insulin and helps prevent hypoglycemia, a common problem after extensive/total pancreas surgery. Dysfunction & Symptoms Pancreatic juices may not reach the duodenum if the duct or papilla is blocked, or if the pancreas is so damaged by disease that it cannot produce adequate bicarbonate and enzymes. Lack of pancreatic juices results in inadequate digestion. Clinically this is noteworthy by the passage of large bowel movements, which a strong odor and are difficult to flush down the toilet because of their high content of fat. Indeed, sometimes patients with pancreatic insufficiency may note an "oil slick" on the toilet water. Excessive fat in the stools is called "steatorrhea." Because food is not absorbed properly patients usually lose weight. These pancreatic enzymes can be replaced, at least to a certain extent, by giving them in the form of a medicine by mouth  so called pancreatic enzyme supplements. It is not usually necessary to replace the missing bicarbonate output. Lack of bile also interferes with digestion (particularly of fats) and can also result in steatorrhea. Lack of bile in the duodenum is usually due to blockage of the main bile duct, or papilla.

The liver continues to produce bile, which then spills backwards into the blood stream. Eventually this causes yellow discoloration of the body (jaundice), first noticeable in the whites of the eyes. If bile does not enter the duodenum, bowel movements lose their usual color, and look like pale putty. When the bile ducts are blocked, retention of bile salts in the blood can result also in considerable itching (pruritus). Blockage of the bile ducts or pancreatic ducts can cause pain due to overdistention. Lack of insulin secretion by the pancreas results in diabetes. It is also possible to have too much insulin when the islets of Langerhans overact, or become tumorous. This results in the blood sugar falling below normal levels, resulting in faintness and eventually coma. Lack or excess of other pancreatic hormones (such as somatostatin, vasoinhibitory peptide, glucagon, etc.) can cause unusual symptoms very rarely. Related Pages What organ in the human body produces bile? | Reference.com What organ in the human body produces bile? A: Quick Answer Bile and pancreatic juices are produced by the liver and pancreas, which are organs that are part of the digestive system.

Biliary juices, or bile, are created in tissue inside the liver called hepatic parenchyma, and then make their way into the biliary ductal system. Small ducts form together and merge into a single river like stream that exits into the duodenum. BBC Science & Nature - Human Body and Mind - Organ Layer Location: Under your diaphragm, more to the right side of your body Physical description: Wedge-shaped, spongy organ Function: To get rid of toxins, to regulate your blood sugar levels and to produce bile Largest internal organ Your liver is your largest internal organ. A big blood vessel, called the portal vein, carries nutrient-rich blood from your small intestine directly to your liver. Chemical processing factory Hepatic cells make up about 60 percent of your liver tissue. These specialised liver cells carry out more chemical processes than any other group of cells in your body. They change most of the nutrients you consume into forms your body cells can use.

They Convert sugars and store and release them as needed, thereby regulating your blood sugar level Break down fats and produce cholesterol Remove ammonia from your body and produce blood proteins, including blood clotting factors Other functions of your hepatic cells are to Detoxify drugs and alcohol Produce bile, which breaks down fats in the food your eat Security guard A second important group of liver cells are the Kupffer cells. They Remove damaged red blood cells Destroy microbes and cell debris Essential for life Because your liver fulfils so many vital functions, you would die within 24 hours if it stopped working. A common sign of a damaged liver is jaundice, a yellowness of your eyes and skin. This happens when bilirubin, a yellow breakdown product of your red blood cells, builds up in your blood. Which organs produce bile? - Quora Quora Produced by the liver and stored in the gallbladder to be secreted from a little tube into the small intestine. 121 Views Written Nov 20 A fact that is probably true, or widely said to be true, but may not be is called a factoid.

People are more likely to believe a statistic if it is an unusual, non rounded number (eg 53% is more believable than 50%) ‘Fact’ comes from the Latin ‘factum’ Peter Wheeler , Pilot Today on my flight, I sat down next to a 10 year old girl who was travelling from Colorado to Connecticut by herself. The plane was stopping in Chicago, where I was getting off to catch my connecting flight. I sat down and pulled out the Lord of the Rings trilogy, and the little girl said "I like your bookmark!" (It was a Lord of the Rings bookmark with a 3D version of Gandalf's head peering ov... Secretion of Bile and the Role of Bile Acids In Digestion Glossary Secretion of Bile and the Role of Bile Acids In Digestion Bile is a complex fluid containing water, electrolytes and a battery of organic molecules including bile acids, cholesterol, phospholipids and bilirubin that flows through the biliary tract into the small intestine. There are two fundamentally important functions of bile in all species: Bile contains bile acids, which are critical for digestion and absorption of fats and fat-soluble vitamins in the small intestine.

Many waste products, including bilirubin, are eliminated from the body by secretion into bile and elimination in feces. Adult humans produce 400 to 800 ml of bile daily, and other animals proportionately similar amounts. The secretion of bile can be considered to occur in two stages: Initially, hepatocytes secrete bile into canaliculi, from which it flows into bile ducts. This hepatic bile contains large quantities of bile acids, cholesterol and other organic molecules. As bile flows through the bile ducts it is modified by addition of a watery, bicarbonate-rich secretion from ductal epithelial cells. In species with a gallbladder (man and most domestic animals except horses and rats), further modification of bile occurs in that organ. The gall bladder stores and concentrates bile during the fasting state. Typically, bile is concentrated five-fold in the gall bladder by absorption of water and small electrolytes - virtually all of the organic molecules are retained. Secretion into bile is a major route for eliminating cholesterol. Free cholesterol is virtually insoluble in aqueous solutions, but in bile, it is made soluble by bile acids and lipids like lecithin.

Gallstones , most of which are composed predominantly of cholesterol, result from processes that allow cholesterol to precipitate from solution in bile. Role of Bile Acids in Fat Digestion and Absorption Bile acids are derivatives of cholesterol synthesized in the hepatocyte. Cholesterol, ingested as part of the diet or derived from hepatic synthesis is converted into the bile acids cholic and chenodeoxycholic acids, which are then conjugated to an amino acid (glycine or taurine) to yield the conjugated form that is actively secreted into cannaliculi. Bile acids are facial amphipathic, that is, they contain both hydrophobic (lipid soluble) and polar (hydrophilic) faces. The cholesterol-derived portion of a bile acid has one face that is hydrophobic (that with methyl groups) and one that is hydrophilic (that with the hydroxyl groups); the amino acid conjugate is polar and hydrophilic.

Their amphipathic nature enables bile acids to carry out two important functions: Emulsification of lipid aggregates: Bile acids have detergent action on particles of dietary fat which causes fat globules to break down or be emulsified into minute, microscopic droplets. Emulsification is not digestion per se, but is of importance because it greatly increases the surface area of fat, making it available for digestion by lipases, which cannot access the inside of lipid droplets. Solubilization and transport of lipids in an aqueous environment: Bile acids are lipid carriers and are able to solubilize many lipids by forming micelles - aggregates of lipids such as fatty acids, cholesterol and monoglycerides - that remain suspended in water. Bile acids are also critical for transport and absorption of the fat-soluble vitamins . Role of Bile Acids in Cholesterol Homeostasis Hepatic synthesis of bile acids accounts for the majority of cholesterol breakdown in the body. In humans, roughly 500 mg of cholesterol are converted to bile acids and eliminated in bile every day. This route for elimination of excess cholesterol is probably important in all animals, but particularly in situations of massive cholesterol ingestion .

Interestingly, it has recently been demonstrated that bile acids participate in cholesterol metabolism by functioning as hormones that alter the transcription of the rate-limiting enzyme in cholesterol biosynthesis. Enterohepatic Recirculation Large amounts of bile acids are secreted into the intestine every day, but only relatively small quantities are lost from the body. This is because approximately 95% of the bile acids delivered to the duodenum are absorbed back into blood within the ileum. Venous blood from the ileum goes straight into the portal vein, and hence through the sinusoids of the liver. Hepatocytes extract bile acids very efficiently from sinusoidal blood, and little escapes the healthy liver into systemic circulation. Bile acids are then transported across the hepatocytes to be resecreted into canaliculi. The net effect of this enterohepatic recirculation is that each bile salt molecule is reused about 20 times, often two or three times during a single digestive phase. It should be noted that liver disease can dramatically alter this pattern of recirculation - for instance, sick hepatocytes have decreased ability to extract bile acids from portal blood and damage to the canalicular system can result in escape of bile acids into the systemic circulation.

Assay of systemic levels of bile acids is used clinically as a sensitive indicator of hepatic disease. Pattern and Control of Bile Secretion The flow of bile is lowest during fasting, and a majority of that is diverted into the gallbladder for concentration. When chyme from an ingested meal enters the small intestine, acid and partially digested fats and proteins stimulate secretion of cholecystokinin and secretin. As discussed previously, these enteric hormones have important effects on pancreatic exocrine secretion. They are both also important for secretion and flow of bile: Cholecystokinin: The name of this hormone describes its effect on the biliary system - cholecysto = gallbladder and kinin = movement. The most potent stimulus for release of cholecystokinin is the presence of fat in the duodenum. Once released, it stimulates contractions of the gallbladder and common bile duct, resulting in delivery of bile into the gut. Secretin: This hormone is secreted in response to acid in the duodenum.

Its effect on the biliary system is very similar to what was seen in the pancreas - it simulates biliary duct cells to secrete bicarbonate and water, which expands the volume of bile and increases its flow out into the intestine. The processes of gallbladder filling and emptying described here can be visualized using an imaging technique called scintography . This procedure is utilized as a diagnostic aid in certain types of hepatobiliary disease. Stomach, Gallbladder and Pancreas | Interactive Anatomy Guide Home > Digestive System > Digestive System of the Lower Torso > Stomach, Gallbladder and Pancreas Stomach, Gallbladder and Pancreas The stomach, gallbladder, and pancreas are three of the most important digestive organs in the human body. These organs work together to produce and store secretions that digest our food into its most basic building blocks. Once digested, these small molecules pass into our intestines to be absorbed and to feed our body’s tissues. These three major organs also produce hormones that help to coordinate their functions and even lead to the feeling of fullness after consuming a meal....

Move up/down/left/right: Click compass arrows Rotate image: Click and drag in any direction, anywhere in the frame Identify objects: Click on them in the image Full Stomach, Gallbladder and Pancreas Description [Continued from above] . . . Anatomy of the Stomach, Gallbladder, and Pancreas Stomach A hollow muscular organ about the size of 2 closed fists, the stomach is located inferior to the diaphragm and lateral to the liver on the left side of the abdominal cavity. The stomach forms part of the gastrointestinal tract between the esophagus and the duodenum (the first section of the small intestine). The wall of the stomach contains several layers of epithelium, smooth muscle, nerves, and blood vessels. The innermost layer of the stomach is made of epithelium containing many invaginations known as gastric pits. The cells of the gastric pits produce gastric juice - an acidic mixture of mucus, enzymes and hydrochloric acid. The hollow portion of the stomach serves as the storage vessel for food before it moves on to the intestines to be further digested and absorbed. At the inferior end of the stomach is a band of smooth muscle called the pyloric sphincter.

The pyloric sphincter opens and closes to regulate the flow of food into the duodenum. Gallbladder The gallbladder is a 3-inch long pear-shaped sac located on the posterior border of the liver. Connected to the bile ducts of the liver through the cystic duct , the gallbladder receives bile transported from the liver for storage on a regular basis to prepare for the digestion of future meals. During digestion of a meal, smooth muscles in the walls of the gallbladder contract to push bile into the bile ducts that lead to the duodenum. Once in the duodenum, bile helps with the digestion of fats. Pancreas The pancreas is a 6-inch long heterocrine gland located inferior to the stomach and surrounded by the duodenum on its medial end. This organ extends laterally from the duodenum toward the left side of the abdominal cavity, where it tapers to a point. The pancreas is considered a heterocrine gland because it has both endocrine and exocrine gland functions. Small masses of endocrine cells known as pancreatic islets make up around 1% of the pancreas and produce the hormones insulin and glucagon to regulate glucose homeostasis in the blood stream.

The other 99% of the pancreas contains exocrine cells that produce powerful enzymes that are excreted into the duodenum during digestion. These enzymes together with water and sodium bicarbonate secreted from the pancreas are known as pancreatic juice. Physiology of the Stomach, Gallbladder, and Pancreas Digestion The stomach, gallbladder, and pancreas work together as a team to perform the majority of the digestion of food. Food entering the stomach from the esophagus has been minimally processed – it has been physically digested by chewing and moistened by saliva, but is chemically almost identical to unchewed food. Upon entering the stomach, each mass of swallowed food comes into contact with the acidic gastric juice, which contains hydrochloric acid and the protein-digesting enzyme pepsin. These chemicals begin working on the chemical digestion of the molecules that make up the food. At the same time, the food is mixed by the smooth muscles of the stomach wall to increase the amount of contact between the food and the gastric juice. The secretions of the stomach also continue the process of moistening and physically softening the food until the food becomes an acidic semi-liquid material known as chyme.

At this point, the stomach begins to push the chyme through the pyloric sphincter and into the duodenum. In the duodenum , the bulk of digestion is completed thanks to the preparation of chyme by the stomach and the addition of secretions from the gallbladder and pancreas. Bile from the gallbladder acts as an emulsifier to break large masses of fats into smaller masses. Pancreatic juice contains bicarbonate ions to neutralize the hydrochloric acid of chyme. Enzymes present in the pancreatic juice complete the chemical digestion of large molecules that began in the mouth and stomach. The completely digested food is then ready for absorption by the intestines . Storage The stomach, gallbladder, and pancreas all function together as storage organs of the digestive system. The stomach stores food that has been ingested and releases it in small masses to the duodenum. The release of small masses of food at a time improves the digestive efficiency of the intestines, liver, gallbladder, and pancreas and prevents undigested food from making its way into feces. As they are accessory organs of the digestive system, the gallbladder and pancreas have no food passing through them.

They do, however, act as storage organs by storing the chemicals necessary for the chemical digestion of foods. The gallbladder stores bile produced by the liver so that there is a sufficient supply of bile on hand to digest fats at any given time. The pancreas stores the pancreatic juice produced by its own exocrine glands so that it is prepared to digest foods at all times. Secretion The stomach, gallbladder, and pancreas all share the common function of secretion of substances from exocrine glands. The stomach contains 3 different exocrine cells inside of its gastric pits: mucous cells, parietal cells, and chief cells. Mucous cells produce mucus and bicarbonate ion that cover the surface of the stomach lining, protecting the underlying cells from the damaging effects of hydrochloric acid and digestive enzymes. Parietal cells produce hydrochloric acid to digest foods and kill pathogens that enter the body through the mouth. Chief cells produce the protein pepsinogen that is turned into the enzyme pepsin when it comes into contact with hydrochloric acid. Pepsin digests proteins into their component amino acids. The mixture of mucus, hydrochloric acid, and pepsin is known as gastric juice.

Gastric juice mixes with food to produce chyme, which the stomach releases into the duodenum for further digestion. The gallbladder stores and secretes bile into the duodenum to aid in the digestion of chyme. A mixture of water, bile salts, cholesterol, and bilirubin, bile emulsifies large masses of fats into smaller masses. These smaller masses have a higher ratio of surface area to volume when compared to large masses, making it easier for them to be digested. The pancreas stores and secretes pancreatic juice into the duodenum to complete the chemical digestion of food that began in the mouth and stomach. Pancreatic juice contains a mixture of enzymes including amylases, proteases, lipases, and nucleases. Carbohydrates entering the small intestine are broken down into monosaccharides by enzymes such as pancreatic amylase, maltase, and lactase. Proteins in the duodenum are chemically digested into amino acids by pancreatic enzymes such as trypsin and carboxypeptidase. Pancreatic lipase breaks triglycerides into fatty acids and monoglycerides.

The nucleic acids DNA and RNA are broken down by nucleases into their component sugars and nitrogenous bases. Hormones Several hormones are used to regulate the functions of the stomach, gallbladder, and pancreas. The hormones gastrin, cholecystokinin, and secretin are secreted by organs of the digestive system in response to the presence of food and change the function of the stomach, gallbladder, and pancreas. Our pancreas produces the hormones insulin and glucagon to affect the behavior of cells throughout the body. Gastrin is a hormone produced by the walls of the stomach in response to the filling of the stomach with food. Food stretches the stomach walls and raises the normally acidic pH of the stomach. G cells in the gastric glands of the stomach respond to these changes by producing gastrin. G cells release gastrin into the blood where it stimulates the exocrine cells of the stomach to produce gastric juice. Gastrin also stimulates smooth muscle tissue of the gastrointestinal tract to increase the mixing and movement of food. Finally, gastrin relaxes the smooth muscles that form the pyloric sphincter, causing the pyloric sphincter to open.

The opening of the pyloric sphincter allows food stored in the stomach to begin entering the duodenum for further digestion and absorption in the intestines. Cholecystokinin (CCK), a hormone produced in the walls of the small intestine , is released into the bloodstream in response to the presence of chyme in the intestine that contains high levels of proteins and fats. Proteins and fats are more difficult for the body to digest than carbohydrates are, so CCK is important in making changes to the digestive system to handle these types of foods. CCK travels through the bloodstream to the stomach, where it slows the emptying of the stomach to give the intestines more time to digest the protein- and fat-rich chyme. CCK also stimulates the gallbladder and pancreas to increase their secretion of bile and pancreatic juice to improve the digestion of fats and proteins. Finally, CCK is detected by receptors in the satiety center of the hypothalamus that control the feeling of hunger. The satiety center reads the presence of CCK as an indication that the body is no longer hungry for food.

Secretin is another hormone produced by the intestinal walls, but unlike CCK, it is produced in response to the acidity of chyme that the stomach releases into the duodenum. Secretin flows through the bloodstream to the stomach, where it inhibits the production of hydrochloric acid by parietal cells. Secretin also binds to receptors in the gallbladder and pancreas, stimulating them to secrete increased amounts of bile and pancreatic juice. Sodium bicarbonate present in pancreatic juice neutralizes the acidity of the chyme to prevent damage to the walls of the duodenum and provides a neutral pH environment for the digestion of chyme. Insulin is a hormone produced by the beta cells of the pancreatic islets of the pancreas. The pancreas produces insulin in response to the presence of high levels of glucose in the blood. Insulin stimulates cells, particularly in the liver and skeletal muscles , to absorb glucose from the blood and use it as an energy source or store it as glycogen. Insulin also stimulates adipocytes to absorb glucose to build triglycerides for energy storage. Our body produces higher levels of insulin following a meal in order to remove glucose molecules from the blood before they can reach high concentrations and become toxic to the body’s cells.

Glucagon is a hormone produced by the alpha cells of the pancreatic islets of the pancreas. Glucagon acts as an antagonist to insulin by stimulating the release of glucose into the bloodstream to raise blood glucose levels between meals. Hepatocytes in the liver store glucose in large macromolecules known as glycogen. Glucagon binding to receptors on hepatocytes triggers the breakdown of glycogen into many glucose molecules, which are then released into the bloodstream. Prepared by Tim Taylor, Anatomy and Physiology Instructor Liver – Anatomy and Function of the Human Liver Sinusoids and Bile Canaliculi Full Liver Description [Continued from above] . . . of growing as quickly as a cancerous tumor to restore its normal size and function. Anatomy of the Liver Gross Anatomy The liver is a roughly triangular organ that extends across the entire abdominal cavity just inferior to the diaphragm. Most of the liver’s mass is located on the right side of the body where it descends inferiorly toward the right kidney . The liver is made of very soft, pinkish-brown tissues encapsulated by a connective tissue capsule.

This capsule is further covered and reinforced by the peritoneum of the abdominal cavity, which protects the liver and holds it in place within the abdomen. The peritoneum connects the liver in 4 locations: the coronary ligament, the left and right triangular ligaments, and the falciform ligament. These connections are not true ligaments in the anatomical sense; rather, they are condensed regions of peritoneal membrane that support the liver. The wide coronary ligament connects the central superior portion of the liver to the diaphragm. Located on the lateral borders of the left and right lobes, respectively, the left and right triangular ligaments connect the superior ends of the liver to the diaphragm. The falciform ligament runs inferiorly from the diaphragm across the anterior edge of the liver to its inferior border. At the inferior end of the liver, the falciform ligament forms the round ligament (ligamentum teres) of the liver and connects the liver to the umbilicus. The round ligament is a remnant of the umbilical vein that carries blood into the body during fetal development.

The liver consists of 4 distinct lobes – the left, right, caudate, and quadrate lobes. The left and right lobes are the largest lobes and are separated by the falciform ligament. The right lobe is about 5 to 6 times larger than the tapered left lobe. The small caudate lobe extends from the posterior side of the right lobe and wraps around the inferior vena cava. The small quadrate lobe is inferior to the caudate lobe and extends from the posterior side of the right lobe and wraps around the gallbladder. Bile Ducts The tubes that carry bile through the liver and gallbladder are known as bile ducts and form a branched structure known as the biliary tree. Bile produced by liver cells drains into microscopic canals known as bile canaliculi. The countless bile canaliculi join together into many larger bile ducts found throughout the liver. These bile ducts next join to form the larger left and right hepatic ducts , which carry bile from the left and right lobes of the liver. Those two hepatic ducts join to form the common hepatic duct that drains all bile away from the liver.

The common hepatic duct finally joins with the cystic duct from the gallbladder to form the common bile duct , carrying bile to the duodenum of the small intestine. Most of the bile produced by the liver is pushed back up the cystic duct by peristalsis to arrive in the gallbladder for storage, until it is needed for digestion. Blood Vessels The blood supply of the liver is unique among all organs of the body due to the hepatic portal vein system. Blood traveling to the spleen , stomach , pancreas , gallbladder, and intestines passes through capillaries in these organs and is collected into the hepatic portal vein . The hepatic portal vein then delivers this blood to the tissues of the liver where the contents of the blood are divided up into smaller vessels and processed before being passed on to the rest of the body. Blood leaving the tissues of the liver collects into the hepatic veins that lead to the vena cava and return to the heart . The liver also has its own system of arteries and arterioles that provide oxygenated blood to its tissues just like any other organ.

Lobules The internal structure of the liver is made of around 100,000 small hexagonal functional units known as lobules. Each lobule consists of a central vein surrounded by 6 hepatic portal veins and 6 hepatic arteries. These blood vessels are connected by many capillary-like tubes called sinusoids , which extend from the portal veins and arteries to meet the central vein like spokes on a wheel. Each sinusoid passes through liver tissue containing 2 main cell types: Kupffer cells and hepatocytes. Kupffer cells are a type of macrophage that capture and break down old, worn out red blood cells passing through the sinusoids. Hepatocytes are cuboidal epithelial cells that line the sinusoids and make up the majority of cells in the liver. Hepatocytes perform most of the liver’s functions – metabolism, storage, digestion, and bile production. Tiny bile collection vessels known as bile canaliculi run parallel to the sinusoids on the other side of the hepatocytes and drain into the bile ducts of the liver. Physiology of the Liver Digestion The liver plays an active role in the process of digestion through the production of bile.

Bile is a mixture of water, bile salts, cholesterol, and the pigment bilirubin. Hepatocytes in the liver produce bile, which then passes through the bile ducts to be stored in the gallbladder. When food containing fats reaches the duodenum , the cells of the duodenum release the hormone cholecystokinin to stimulate the gallbladder to release bile. Bile travels through the bile ducts and is released into the duodenum where it emulsifies large masses of fat. The emulsification of fats by bile turns the large clumps of fat into smaller pieces that have more surface area and are therefore easier for the body to digest. Bilirubin present in bile is a product of the liver’s digestion of worn out red blood cells. Kupffer cells in the liver catch and destroy old, worn out red blood cells and pass their components on to hepatocytes. Hepatocytes metabolize hemoglobin, the red oxygen-carrying pigment of red blood cells, into the components heme and globin. Globin protein is further broken down and used as an energy source for the body.

The iron-containing heme group cannot be recycled by the body and is converted into the pigment bilirubin and added to bile to be excreted from the body. Bilirubin gives bile its distinctive greenish color. Intestinal bacteria further convert bilirubin into the brown pigment stercobilin, which gives feces their brown color. Metabolism The hepatocytes of the liver are tasked with many of the important metabolic jobs that support the cells of the body. Because all of the blood leaving the digestive system passes through the hepatic portal vein, the liver is responsible for metabolizing carbohydrate, lipids, and proteins into biologically useful materials. Our digestive system breaks down carbohydrates into the monosaccharide glucose, which cells use as a primary energy source. Blood entering the liver through the hepatic portal vein is extremely rich in glucose from digested food. Hepatocytes absorb much of this glucose and store it as the macromolecule glycogen, a branched polysaccharide that allows the hepatocytes to pack away large amounts of glucose and quickly release glucose between meals.

The absorption and release of glucose by the hepatocytes helps to maintain homeostasis and protects the rest of the body from dangerous spikes and drops in the blood glucose level. (See more about glucose in the body .) Fatty acids in the blood passing through the liver are absorbed by hepatocytes and metabolized to produce energy in the form of ATP. Glycerol, another lipid component, is converted into glucose by hepatocytes through the process of gluconeogenesis. Hepatocytes can also produce lipids like cholesterol, phospholipids, and lipoproteins that are used by other cells throughout the body. Much of the cholesterol produced by hepatocytes gets excreted from the body as a component of bile. Dietary proteins are broken down into their component amino acids by the digestive system before being passed on to the hepatic portal vein. Amino acids entering the liver require metabolic processing before they can be used as an energy source. Hepatocytes first remove the amine groups of the amino acids and convert them into ammonia and eventually urea. Urea is less toxic than ammonia and can be excreted in urine as a waste product of digestion.

The remaining parts of the amino acids can be broken down into ATP or converted into new glucose molecules through the process of gluconeogenesis. Detoxification As blood from the digestive organs passes through the hepatic portal circulation, the hepatocytes of the liver monitor the contents of the blood and remove many potentially toxic substances before they can reach the rest of the body. Enzymes in hepatocytes metabolize many of these toxins such as alcohol and drugs into their inactive metabolites. And in order to keep hormone levels within homeostatic limits, the liver also metabolizes and removes from circulation hormones produced by the body’s own glands. Storage The liver provides storage of many essential nutrients, vitamins, and minerals obtained from blood passing through the hepatic portal system. Glucose is transported into hepatocytes under the influence of the hormone insulin and stored as the polysaccharide glycogen. Hepatocytes also absorb and store fatty acids from digested triglycerides. The storage of these nutrients allows the liver to maintain the homeostasis of blood glucose.

Our liver also stores vitamins and minerals - such as vitamins A, D, E, K, and B12, and the minerals iron and copper - in order to provide a constant supply of these essential substances to the tissues of the body. Production The liver is responsible for the production of several vital protein components of blood plasma: prothrombin, fibrinogen, and albumins. Prothrombin and fibrinogen proteins are coagulation factors involved in the formation of blood clots. Albumins are proteins that maintain the isotonic environment of the blood so that cells of the body do not gain or lose water in the presence of body fluids. Immunity The liver functions as an organ of the immune system through the function of the Kupffer cells that line the sinusoids. Kupffer cells are a type of fixed macrophage that form part of the mononuclear phagocyte system along with macrophages in the spleen and lymph nodes . Kupffer cells play an important role by capturing and digesting bacteria, fungi, parasites, worn-out blood cells, and cellular debris. The large volume of blood passing through the hepatic portal system and the liver allows Kupffer cells to clean large volumes of blood very quickly.

Prepared by Tim Taylor, Anatomy and Physiology Instructor What Does the Liver Do? | Were You Wondering… Home Anatomy What Does the Liver Do? What Does the Liver Do? Posted By: Katrina Cain on: July 28, 2009 Tweet Don’t mess with your liver. It serves a vital function in almost every system in your body; from hormone and digestive enzyme production to blood filtration and the last stop in chemical digestion of medications. It is both an endocrine and exocrine organ, and along with the heart, brain and pancreas is an organ that we cannot live without. Read further to find out just what the liver does in your body. Exocrine Functions An exocrine organ secretes substances that leave your body – think “exit” and “exocrine”. Your digestive tract is one long tube, open at both ends that receives enzymes and other materials to enable nutrient absorption. Mammary glands produce milk and mucus glands secrete mucus; all of which are destined to leave the body. In contrast, endocrine organs secrete chemicals into the bloodstream for use by the body. The adrenal glands release adrenaline into the blood to physically prepare us for danger. The hypothalamus produces a myriad of hormones to regulate bodily functions.

The liver produces bile that is stored in the gallbladder to be secreted into the small intestine before eventually leaving the body; making bile production an exocrine function. Bile emulsifies fats – breaks the large lipid molecules into smaller pieces, creating more surface area to ease digestion. This is why people without gallbladders can’t have a lot of fatty foods at one time. The liver is able to produce enough bile for immediate use, but can’t stockpile enough bile to digest a Big Mac and large fries. Your liver also manufactures some very important hormones (endocrine function). It produces Insulin-Like Growth Factor (IGF 1); a hormone responsible for stimulating body growth in children. Thrombopoietin is a hormone produced by the liver that regulates platelet production in your bone marrow. “Thrombo” refers to blood clotting and “poietin” refers to stimulating cell multiplication. I am a big believer in breaking down words into their roots. The body becomes much easier to understand if you know anything “hepatic” is pertaining to the liver, “angio” to the heart, “renal” to the kidneys and so on.

Your liver, along with your kidneys, are an important organ in glucose metabolism. The liver converts glucose into glycogen. Glycogen provides the body with short term energy storage. Long term energy storage is contained in fat cells. Muscle cells can also convert glucose to glycogen. “Gluco” refers to sugar. The liver converts glycogen back to glucose for immediate use. Gluconeogenesis is the process of making glucose (genesis) from “new” products. Specifically, this refers to making glucose from amino acids, lactate and other non-sugar substances. Gluconeogenesis occurs in times of fasting and exercise – generally after all easily available reserves have been used up. To summarize, glycogenesis is the opposite of glycogenolysis (lysis means to break apart). The liver makes cholesterol and tryglycerides; important components of hormone production. Thank your liver for those elevated cholesterol levels. Through a relatively complicated chemical synthesis, the liver converts glucose into triglycerides by attaching a glycerol to every three glucose. Cells in the body use triglycerides in their endoplasmic reticulum; the site of protein and hormone production (endo means inside and plasma refers to the cytoplasm inside a cell).

Fatty liver is a disease in which the liver enlarges with excess triglycerides. Since the liver is the site of triglyceride manufacture, a vicious cycle occurs when the body has too much glucose, the liver busily makes the glucose into triglycerides at an increased rate to match those higher levels. The body uses as much triglycerides as it can, and the rest builds up in the liver; having no where else to go. Alcoholism and obesity are common causes of fatty liver disease. Do you eat fois gras? You are eating the diseased liver of obese birds. Farmers force feed geese and ducks corn boiled in fat to create fatty liver disease. It is the excess fat that gives their liver the rich and buttery taste. There are major ethical debates world wide about this practice, but I digress.. The liver is where old red blood cells go to die. Bilirubin and biliverdin are waste products from red blood cell metabolism. Some is added to bile to aid in fat digestion and some is filtered through the kidneys to give urine its trademark yellow color. The bile portion makes its way through the small and large intestine to give feces its trademark brown color.

Jaundice, the disease in which the skin and eyes become yellow results from a blood excess of bilirubin. The liver normally collects and secretes bilirubin into bile, but if it is not functioning properly, bilirubin builds up in your blood and becomes toxic. The liver is the site of drug metabolism and in some cases drugs can become temporarily more toxic to the body during the digestion process as their constituents become more concentrated. Some drug metabolites are secreted into bile and others into urine. In addition to drug metabolism, the liver has cells that filter antigens out of the blood. Anti in this case refers to antibody and gen refers to generating; so antigen literally means “antibody generating”. The liver is one of the many immunological organs in the human body. The liver stores vitamins and minerals for short and long term use including Vitamin A, Vitamin D, Vitamin B12, iron and copper and in case I haven’t already made a case for taking care of your liver, be aware that it is responsible for making albumin, the plasma protein responsible for maintaining blood osmolarity – the concentration of dissolved solutes for a given amount of liquid.

If your blood osmolarity is out of whack, you risk bleeding internally. The cells in your body will either shrink up and die from losing water or swell up and burst from taking in too much water. One more major function; the liver makes angiotensinogen, a precursor to angiotensin, the hormone responsible for increasing blood pressure in times of fluid loss, or elevated blood cortisol levels. With all of these major functions, it is a wonder that we don’t get sick with liver related problems even more than we already do. Take heart (or liver – tee hee); the liver is the only human organ capable of regeneration. You can grow a new liver from only 25% of a full liver! Someone doesn’t have to die for you to receive a transplant! Related Posts

Question: Which organ of the body produces bile
Answer: The liver